info/tev discussion.pdf · 2007. 1. 16. · •field training eliminate unnecessary replacement...

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Sporlan Valve DivisionParker Hannifan/CIC Group

Matt McGrath, SW Regional Sales Manager

Bob Dolan, Sales Engineer - Atlanta

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Why Discuss TEVs Today?

• Expansion Valves are you’re Future

• Important Component to Reaching 13 SEER

• Provide Better Performance over EntireOperating Range

• Protect Compressor from Flood back

• Better Performance with low/high charge

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How TEVs Improve SEER!

• TEVs close when compressor is off !!!!!

� Isolates most of the Charge in OutdoorUnit

� Evaporator starts cooling air faster onstart up

• However, TEVs Improve Efficiency

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TEVs vs Cap Tube/Restrictors

Outdoor Temperature ºF

EvaporatorSuperheat

Flood

Fixed Restrictor

TEV

TEV Provides Improved Efficiency

CapacityRating Point

TEVProtects

Compressor

© Copyright 2002 By Sporlan Valve Company, Washington, MO TEV-03 (10-1890-2/04)

COMPRESSOR

CONDENSER

EVAPORATOR

AEVAUTOMATICEXPANSION

VALVE

EEVELECTRONICEXPANSION

VALVE

FIXEDRESTRICTOR

CAPILLARYTUBE

TEV


The Function of a Thermostatic Expansion Valve

To keep coil as completely refrigeratedas possible under all load conditions


SuctionPressureControl

HumidityControl

TemperatureControl


Basis for Nominal TEV Capacities

TNAREGIRFER

a431 22 A404 A014 705 717

isp-tropssorcaporderusserP 06 001 001 061 001 041

,erutarepmetrotaropavE F° °04 °04 °04 °04 °04 °5

,VETgniretneerutarepmetdiuqiL F° °001 °001 °001 °001 °001 °68


EVAPORATOR

Feed Me

More!

The Valve Responds to Input from the Bulb


Diaphragm

Adjusting Stem

Capillary Tube

Pin

Spring

Pushrods

Principal Parts of Any TEV

Bulb

Seat

Spring Guide


Three Factors Effecting Normal TEV Capacity

PORT SIZE

PIN ANGLE(some are flat)

STROKE


50°F AIR

COMPRESSOR

EVAPORATOR

Bulb

EvaporatorPressure

SpringPressure

TEV Controlled Superheat


Three Fundamental PressuresBulb Pressure = Evaporator Pressure + Spring Pressure

1 2 3

OpeningForce

ClosingForce

2 EvaporatorPressure

3

SpringPressure

1BulbPressure


InternalEqualizer

ExternalEqualizer

Fitting

PushRods

CloseToleranceFit

EvaporatorOutlet

PressurePushRods

ValveOutletPressure

Valve with INTERNALEqualizer

Valve with EXTERNALEqualizer


TEV Pressure Balance30°F Sat.55 psig

COMPRESSOR

EVAPORATOR

20°F Sat.43 psig

∆ p 6 psi49 psig

SPRING12 psig

TNAREGIRFER

GNITAROPAVEERUTAREPMET F°

04 02 0 02- 04-

isp-PORDERUSSERP

a431,21 2 5.1 1 57.0 —

22 3 2 5.1 0.1 57.0

705,205,A404 3 5.2 57.1 52.1 0.1

717)ainommA( 3 2 5.1 0.1 —


Temperature (°F)

Liquid Completely Vaporized

TemperaturePressure

(Liquid

Prese

nt

)

No LiquidIn Bulb (Gas)

Pres

sure

(psi

g)

Bulb

EvaporatorPressure

Gas Charged and Type “CP” Air Conditioning Charged Element


Type CP Air Conditioning and GA Charges

FlowMaster®


The FlowMaster® element

1. Can successfully reduce or even eliminate hunting

2. Provide steady performance

Types CP Air Conditioningand GA Charges on Floodback


1. Opens slowly - steady response

2. Closes quickly - prevents floodback

Anti-Hunt Principle

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2001 Sporlan/Trane TEV Field Returns

76%

24%

Non Manfacturing Causes All Manufacturing Defects

% of items Returned

Approx.1000 ppm Field Returns

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Break Down of Non ManufacturingCauses

0%

5%

10%

15%

20%

25%

30%

35%

40%

No Failure Found Broken Cap-Tube

Field Damaged Contamination

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Breakdown of ManufacturingDefects

0%

2%

4%

6%

8%

10%

12%

Charge Leak External Leak Incorrect Setting IncorrectAssembly

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Sporlan & Trane Working Togetherto Reduce TEV Warranty Issues

• Field Training� Eliminate Unnecessary Replacement

• Improved Cap Tube Processing� In 2003 Sporlan Implemented Numerous

Improvements to Prevent Tube from Breaking� In 2006 TEVs will be Factory Installed

• Sporlan Leak Task Team� Continuous Improvements to Reduce Leaks

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Check Valve Operation

ContainsInternal

Check Valve

•Provides Low ∆P Reverse Flow for Heat Pump Systems•Eliminates External Check•Reduces Braze Joints

Model: CBBIE

The liquid line joins various high side components, BUT its primary function . . .

© Copyright 2002 by Sporlan Valve Company, Washington, Missouri SS-06(10-0249-7-02)

supply vapor free liquidto the TEV inlet, despite pressure loss from 1 Flow friction

2 Vertical lift

3 Flow through accessories


Inlet


How much subcooling is needed?Vertical lift is 20’ so pressure loss is about . . . . . . . . . 10 psiPressure loss due to flow friction is about . . . . . . . . . . 4 psi Pressure loss across accessories is about . . . . . . . . . . 4 psi

Total pressure drop . . . . . . . . . . . . . . . . . . . . . . . . . 18 psi

Example: R-22


A Condensing pressure for R-22 is 220 psiand saturation temperature is . . . . . . . . . . 108°F (220 psig)

B Because of losses, pressure at TEV inlet is 202 psi and saturation temperature is . . . 102°F (202 psig)

C Subcooling required is . . . . . . . . . . . . . . . 6°F

B

A


TEV’s primary job:

supply the properamount of refrigerantunder all load conditions


Superheat

2 Actual temperature at bulb minus saturated temperature (corresponding to pressure at bulb)

PRESSUREPRESSUREPSIPSI

PRESSUREPSI

29


R-22

Actual temperature at bulb . . . . . . . . . . . . .52°F

Saturated temperature corresponding to 68.5 psig . . . . . . . . . . . . .40°F

Operating superheat . . . . . . . . . . . . . . . . .12°F

PRESSURE PRESSURE

PSI PSI

PRESSUREPSI

52

68.5psig

And it’s easy toblame the valve



Bulb location is importantMount on a horizontal free draining section on the suction line at the evaporator outlet

Important conditions are:

1 Thermal contact

2 Circumferential location


1 Thermal ContactMount on straight, clean section parallel to suction line

not on fitting

not with tape

yes!

no!Flow


2 Circumferential Location

On larger lines, positionbulb at 4 o’clockor 8 o’clock

Never mount at bottom


2 No need to disassemble, but...

a Direct flame away from body

b Avoid oversized torch tip

c Avoid excessive heat on diaphragm

d Keep flame away from bulb

3 Use dry nitrogen for a reducing atmosphere


Evacuate non-condensibles andwater from the system using awell maintained vacuum pump

Why not use the system’s compressor?1 Not designed as a vacuum pump2 Not properly lubricated3 Compressor oil may be contaminated4 Compressor motor may overheat


4 Basic Scenarios

1 Feeds not enough

2 Feeds too much

3 Feeds not enough, then too much

4 Floodback only during start up


1 Moisture, dirt, wax2 Undersized valve3 High superheat adjustment4 Gas charge condensation5 Dead thermostatic element6 Wrong thermostatic charge7 Evaporator pressure drop –

no external equalizer8 External equalizer location

9 Restricted or capped externalequalizer

10 Low refrigerant charge11 Liquid line vapor – vertical lift,

high friction loss, long or smallline, plugged drier or strainer

12 Low pressure drop across valve –same as no. 11 above, undersizeddistributor nozzle or circuits, low condensing pressure

PR

ESSUR

EP

RESSU

RE

PSI

PSI

PR

ESSUR

E

PSI

LOW

HIGH

Symptom See-SawCauses Feeds not

enough


Causes

PR

ESSUR

EP

RESSU

RE

PSI

PSI

PR

ESSUR

EP

SI

LOW

HIGH

Symptom See-Saw

1 Oversized valve

2 TEV seat leak

3 Low superheat adjustment

4 Bulb installation: poor thermal contact, warm location

5 Wrong thermostatic charge

6 Bad Compressor – low capacity

7 Moisture, dirt, wax

8 Incorrectly located external equalizer

Feeds too

much


PR

ESSUR

EP

RESSU

RE

PSI

PSI

PR

ESSUR

E

PSI

LOWLOW

Causes1 Low load –

not enough air, dirty air filters,air too cold, coil icing

2 Poor air distribution

3 Poor refrigerant distribution

4 Improper compressor –evaporator balance

5 Evaporator oil logged

6 Flow from one TEV affecting another’s bulb

Symptom See-Saw

Hunts –feeds not

enough,then too

much


Hunting and Cycling

SystemSingle Compressorand Evaporator

Multiple Evaporators with one compressor or compressors with capacity reduction

SymptomsVariation in both suctionpressure and superheat

Superheat variation but only slight suction pressure change

Feeds not

enough,then too

much


1 Oversized valve

2 TEV seat leak

3 Low superheat adjustment

4 Bulb installation: poor thermal contact, warm location

5 Compressor discharge valve leak

6 Solenoid valve seat leak

7 Compressor in cold location

8 Suction line in cold location

9 Evaporator draining freely to compressor

10 Interrupted pump down

11 Restricted or plugged externalequalizer

12 Wrong thermostatic charge

Flood-back only during start-upCauses Flood-

back


Valve performance cannever be restored orimproved by physicalforce

Disassembly might uncover the problem


Eliminate the problem

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Additional Training Available

• Training will Reduce Warranty Costs

• Call on Sporlan to Assist with Deal &Contractor Training in Your Area

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Thank You&

Questions

info/tev discussion.pdf · 2007. 1. 16. · •field training eliminate unnecessary replacement...

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